1. Field of the Invention
The present invention relates to a liquid discharge recording head for performing a recording operation by discharging a liquid, such as ink, and a liquid discharge recording head cartridge including the recording head.
2. Description of the Related Art
A related liquid discharge recording head discharges liquid drops, such as ink drops, from a plurality of discharge openings by generating and making use of mechanical or thermal energy. In such a liquid discharge recording head, flow path resistances to the flow of liquid between a liquid supply opening and the discharge openings are adjusted by the shapes of the nozzles to thereby determine characteristics, such as liquid discharge amount and refill frequency. More specifically, the adjustment of the flow path resistances by the shapes of the nozzles is performed by adjusting the width and the length of the flow paths. For example, Japanese Patent Laid-Open No. 7-137293 discloses a method of forming nozzles having different flow path resistances by changing the widths of the flow paths according to the nozzles.
In recent years, a liquid discharge recording head which can perform high-speed and high-quality recording as a result of disposing its nozzles close to each other at a high density has been proposed. As the nozzles are disposed closer together at a higher density, the space for disposing one nozzle becomes narrow, thereby tending to place constraints on the manufacturing of the nozzles. Therefore, in a liquid discharge recording head whose nozzles are disposed at a density of at least 90 dpi, it is necessary to dispose the nozzles and heating resistors (heaters) in what is called a staggered arrangement in order to dispose adjacent nozzles so that the distances from discharge openings to a liquid supply opening differ.
When the nozzles and the heaters are disposed in a staggered arrangement, in order to make the liquid discharge amounts from all of the nozzles the same, the discharge characteristics of the nozzles having large distances from the discharge openings to the liquid supply opening and the distance characteristics of the nozzles having small distances from the discharge openings to the liquid supply opening must be about the same. This is generally achieved by making the flow path resistances of the long nozzles small and the flow path resistances of the short nozzles large. In order to make the flow path resistances of the long nozzles small, it is necessary to increase the widths of the flow paths. However, when the nozzles are disposed at a high density of at least 900 dpi, it is difficult to increase the widths of the flow paths due to, as mentioned above, the narrow space for disposing the nozzles and manufacturing constraints.
In addition, in order to increase refill frequency after discharging liquid, it is necessary to reduce the lengths of the flow paths by bringing the discharge openings and the liquid supply opening closer to each other at all of the nozzles. However, for the nozzles having relatively small distances from the discharge openings to the liquid supply opening, there is a limit as to how close these discharge openings can be brought close to the liquid supply opening due to nozzle disposing space and manufacturing constraints. Therefore, it is difficult to provide the short nozzles with the proper flow path resistances in accordance with those of the long nozzles. Consequently, the refill frequency cannot be sufficiently increased.
Accordingly, when the nozzles and the heaters are disposed in a staggered arrangement at a high density, it is very difficult to adjust the flow path resistances by changing the widths and lengths of the flow paths in accordance with the lengths of the nozzles due to nozzle disposing space and manufacturing constraints. In addition, in order to make the space between the liquid supply opening and the flow paths as small as possible, it may be desirable not to dispose a nozzle filter between the flow paths and the liquid supply opening in a related liquid discharge recording head.